North Melbourne's Jamie Macmillan has signed a two-year contract extension with the Roos, tying him to the club until the end of the 2019 season.

Macmillan's current contract expires at the end of next season, but the Kangaroos have secured the young leader away from the dangers of free agency a year early.

The 24-year-old, who is the youngest member of the club's leadership group, said he never entertained the idea of playig for another club.

"I'm really happy with where the club's at and how I've fitted in here and how I enjoy life at North Melbourne, so (free agency) didn't really cross my mind," Macmillan said.

"I think for me it's just the ability to identify things on field and understanding the game, helping other guys out with their structures.

"That's probably what, in a sense, got me in the leadership group, but now I'm learning more about the off-field side of things and the ability to identify things we can improve around the club, and building a really strong culture which we're really proud of.

"So that's something that I'm working really hard on."

Macmillan has played 84 career games since being selected with pick No.37 in the 2009 National Draft.